The purpose of this project is to construct in vitro models of epidermal cell cytotoxicity as mechanisms of skin disease. Although antibody dependent cellular cytotoxicity (ADCC) is the mechanism to be most actively studied, we will also examine complement mediated lysis, natural killing, and eventually classical cell mediated cytotoxicity of epidermal targets. These in vitro models will be used to study our hypothesis that ADCC of epidermal cells is an important mechanism of cutaneous lupus erythematosus, using ultraviolet light transformed cells or epidermal cells specifically coated with nucleoprotein antigens. Similar experiments will be performed using herpes simplex antigen coated epidermal cells and endothelial cells to construct an in vivo model of post-herpetic erythema multiforme. Models of ADCC in pemphigus vulgaris, bullous pemphigoid, lichen planus, and maculopapular drug eruptions will also be constructed.